Why didn’t the Red Sox use Craig Kimbrel in the opener?

ST. PETERSBURG, Fla. — This was going to happen. It’s just that no one figured it would happen so fast, and in such glaring fashion.

Alex Cora found his way under the Boston managerial microscope in Game 1, thanks to a startling bullpen meltdown that transformed a 4-0, eighth-inning lead into a 6-4 loss to the Rays.

There will be questions about the specific inflexion points, particularly the non-usage of Craig Kimbrel in the eighth inning, something Cora said days ago that he wouldn’t do at the start of the season given that the All-Star is still in the equivalent of a spring training buildup. But we learned something else about Cora: He sticks to a plan.

It sounds like a small thing, but it’s not. The man who managed Cora when he played in Boston, Terry Francona, received raves for refusing to let a game situation and the promise of an immediate win trump his sense of how to preserve the well-being of his roster for the long haul.

Francona discussed it many times: There were instances when accepting an increased risk of one loss was the right thing to do for the sake of his team’s well-being in the bigger picture. In the first game of his managerial career, Cora — who has spoken all spring about workloads and his desire to manage playing time in an effort to achieve peak performance late in the year — showed a similar commitment, in a way that may have contributed to his 0-1 record as a manager.

He watched the wheels come off as Joe Kelly and Carson Smith struggled to find the strike zone during that six-run eighth.

How hard is it for a first-time manager to wear that first loss when it comes as a result of sticking to principles?

“Any time, when you know you made the right moves, you don’t second-guess it,” said Red Sox bench coach Ron Roenicke, who managed the Brewers from 2011 until early 2015. “[Cora] and [pitching coach Dana LeVangie] had it pretty much mapped out ahead of time. I was in the office when they were talking about it. That was set up ideally for what we wanted to do — ideally. Go six innings from our big boy, which is great, then off to the next two guys, get to Kimbrel. It was set up perfect for us. We just didn’t pitch the way we know we’re going to.

“It’s just baseball. The saying is that you’ve got to play through 27 outs. It’s so true,” Roenicke continued. “Alex and Dana did a great job of planning this. Our players who are going to do well this season didn’t get it done tonight. That’s the way it goes.”

Cora suggested that roughly 15 days from now, he might consider using Kimbrel as the eighth-inning fireman. So why not in the middle of the eighth inning Thursday?

The Sox were concerned that a hurried buildup to get ready for the game rather than one that followed more familiar protocols, along with the increased stress of a situation with traffic all over the bases, would represent a potential injury risk for a pitcher. Kimbrel was limited to two spring appearances as a result of his need to spend much of March in Boston to tend to his hospitalized daughter, Lydia.

They felt comfortable with a blueprint of navigating the middle innings with Matt Barnes, Kelly, and Smith leading up to Kimbrel in the ninth. They did not feel comfortable with Kimbrel for anything but three outs in a clean ninth.

“The whole idea when you plan out things is to get through the entire season, you better take care of your guys. We decided with Kimbrel we were going to take care of him. He wasn’t going to do that extra [work] right now,” said Roenicke. “That’s the way you do it. We’re not going to go anywhere if we have to always bring Kimbrel in the eighth inning. We’ve got a good bullpen. Joe’s going to pitch well. Smith’s going to pitch well. They just didn’t pitch well today. They’re going to be really good this year.”

There will come a time when Cora will — and should — be open to employing Kimbrel in different high-leverage situations. But even when he does so, the team will still need other relievers to record crucial outs. Will Barnes, Kelly, and Smith prove up to the task? That’s a bet that the Sox made this offseason, and one that’s likely to be revisited.

Kelly’s performance, in particular, puzzled. Why did he have what he described as a “pretty pathetic” performance? Why did a pitcher whose strong 2017 campaign was built on a mix of roughly one breaking ball (either curveball or slider) for every two four-seam fastballs instead open his outing by throwing two-seam fastballs on 22 of his first 24 pitches — thus allowing the Rays to sit on the sort of narrow velocity range that took guesswork out of their takes?

Was Christian Vazquez too cautious about using a mound visit — the Sox used just one of their allotted six trips to the mound — to consult with Kelly either to change his mix or just to buy him a chance to catch his breath? It wasn’t until LeVangie made a trip to the mound that Kelly started mixing his pitches, though even that proved unsuccessful as he walked his final batter, Carlos Gomez, while getting a swing at just one of his four sliders out of the zone.

These are questions that the Red Sox likely will revisit and explore in the days to come. The idea of entrusting the eighth to pitchers other than Kimbrel?

“I don’t think we would have changed it. We wanted the guy in there who started that inning,” said LeVangie. “Long season ahead of us, we expect to win a lot of games. We expect that guys that underperformed tonight to perform at their level. It’s just the way it is. We’ll do a better job next time.”

The Red Sox have 161 games to test that belief. In his first game as manager, Cora showed that he’ll remain mindful of that bigger picture rather than focused narrowly on a single moment in time.

Alex Speier can be reached at alex.speier@globe.com. Follow him on twitter at @alexspeier.